Not 'most girls'. That's a completely pointless generalisation.You have to pull your underwear down anyway, so sometimes it's just as easy to hike them both down at the same time. Same goes for anyone who usually wears trousers or shorts, you're used to pulling them down, so pull your skirt down too.It's besides the point anyway, because chances are she pulled up her skirt, and when pulling it down she accidentally tucked some of it into her thong, which i've definitely done before.

I assumed she flipped her skirt up, thong down... used the toilet... Then it's on pulling your underwear back up that you get your skirt hitched up (normally at the back - particularly bad for a thong).